The present invention relates generally to remote reading of meters and more particularly to a device and method for automatically reading meters at subscriber telephone stations from a remote location, such as a central office, over non-dedicated telephone lines in response to a call initiated by the central office.
Over the last several years a number of different systems have been proposed for automatically reading utility and other types of meters from a remote location for the purpose of eliminating the high labor costs involved in door-to-door meter reading and for providing more up-to-date information. Unfortunately, for one reason or another, none of these systems have come into wide spread use.
Many of these proposed systems have involved using existing, non-dedicated, telephone lines as the communications medium for transferring the meter information and have involved obtaining the information in response to a telephone call initiated by the collecting station. The main advantage of using non-dedicated telephone lines is that it does not require installing additional communication lines. The main advantages of transferring the information pursuant to a call made by the collecting station are that it does not require complex answering equipment at the collecting station to insure that all incoming calls will be answered in an orderly and efficient manner and does not involve the use of selectively operable automatic dialing devices at each one of the locations containing utility meters which are to be read. One of the problems with such systems, however, has been the unavoidable ringing of the telephone at the subscriber station pursuant to the call initiated by the collecting office. In order to avoid this nuisance to the subscriber, a number of different techniques have been suggested.
One such technique involves using special telephone company line test circuits which will not activate the bell in the telephone at the subscriber station for connecting the collecting station with the subscriber station. One of the problems with this technique is that it requires installing additional equipment at the telephone company exchange. Also, the technique requires telephone company approval. An example of a system employing this technique is described in U.S. Pat. No. Re. 26,331 reissued on Jan. 9, 1968, to Brothman et al on original U.S. Pat. No. 3,142,726 dated July 28, 1964.
Another technique involves the use of a ring muting circuit at the telephone subscriber station for muting a portion of the first ring and the use of sequential ringing signals having a different spacing from normal ringing signals for the call from the collecting office. One of the problems with this technique is that it involves complicated circuitry at the central office, and some modification of the circuitry at the telephone exchange and at the subscriber station. Another problem with this technique is that a portion of the first ring on every incoming call is muted, which is rather objectionable. An example of this technique is disclosed in U.S. Pat. No. 4,126,762 issued on Nov. 21, 1978, to Martin et al.
Still aother technique involves disconnecting the subscriber's telephone from the telephone lines for a certain time period each day and then connecting the telephone wires directly to a meter reading device connected to the utility meters during that time period. The meter reading device responds to an incoming call by transmitting out the meter data. One problem with this arrangement in that normal telephone service is completely disrupted for that period. Another problem with this arrangement is that all incoming calls made during that time period, including calls made by parties other than the collecting station, will be connected to and answered by the meter reading device. Once answered, the meter data will be sent out over the telephone lines, even though the caller may not be the collecting station. An example of this arrangement is also disclosed in the above noted U.S. Pat. No. 4,126,762.
A further technique involves the use of switch controlled delaying apparatus at the subscriber station arranged so that when a call is received at the subscriber station it is not connected to the telephone until a sufficient amount of time has elapsed to permit call answering apparatus at the subscriber station to receive a specially coded signal sent between the first ringing signal and the second ringing signal indicating that the call is from the collecting station. One of the objectionable aspects of this technique is that the first ringing signal is suppressed. An example of this arrangement is described in British Pat. No. 905,411 published Sept. 5, 1962, to Kienast.
Other known prior art includes U.S. Pat. Nos. 3,049,592; 3,231,670; 3,266,018; 3,362,971; 3,376,389; 3,508,243; 3,551,597; 3,558,357; 3,564,143; 3,742,142; 3,842,206; 3,868,640; 3,899,639; 3,902,016; 3,922,492; 3,936,617; 3,937,890; 4,002,837; 4,004,097; 4,022,927; 4,059,727; 4,086,434; 4,126,472; 4,151,371; 4,169,290; 4,180,709; 4,241,237; Bell Laboratories Record, Volume 48 No. 4 (1970) pp. 104-109; the American City and County (Dec. 1975) pp. 47-48; and IBM Technical Disclosure Bulletin, (Feb. 1971), Vol. 13, No. 9, pp. 2682-2683.